Proving I-A is Invertible with A^m=0

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SUMMARY

The discussion centers on proving that the matrix \(I - A\) is invertible given that \(A^m = 0\) for a positive integer \(m\). The key insight is to utilize the series \(\sum_{j=0}^m A^j\) and demonstrate that \((I - A)\sum_{j=0}^m A^j = I\). This confirms that \(I - A\) has an inverse, specifically \(\sum_{j=0}^m A^j\), establishing the invertibility of \(I - A\) in the context of linear algebra.

PREREQUISITES
  • Understanding of matrix operations and properties
  • Familiarity with the concept of nilpotent matrices
  • Knowledge of the identity matrix and its role in linear algebra
  • Basic comprehension of matrix series and summation notation
NEXT STEPS
  • Study the properties of nilpotent matrices in linear algebra
  • Learn about matrix inversion techniques and criteria
  • Explore the implications of the Cayley-Hamilton theorem
  • Investigate the role of the identity matrix in matrix transformations
USEFUL FOR

Students of linear algebra, mathematicians, and anyone interested in matrix theory and its applications in solving systems of equations.

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Homework Statement



Let A be a nxn matrix, and I the corresponding identity matrix, both in the real numbers ℝ. Assume that A^m=0 for a positive integer m. Show that I-A is an invertible matrix.

Homework Equations





The Attempt at a Solution

 
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Hint what is

$$\sum_{j=0}^m \, A^j$$

what is

$$(I-A)\sum_{j=0}^m \, A^j$$
 

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